Side Of Substrate Research Articles

Corrosion behavior of three heat‐resistant steels for turbine system in steam at 600°C and 20 MPa

AbstractThe corrosion behavior of KT5916, 2Cr11Mo, and Co3W3 in high‐temperature and high‐pressure steam at 600°C, and 20 MPa were investigated. The kinetic weight gain curves of KT5916 and Co3W3 nearly followed a parabolic law. Oxide scale exfoliation was found in all steels. The oxide layer structural distribution of the three heat‐resistant steels was Fe3O4 layer and FeCr2O4 layer from the gas side to the substrate side, and the critical criterion for the formation of Fe2O3 oxide was 509.3°C. Under the influence of growth stress, the oxide film of the three heat‐resistant steels experienced a stable oxide layer, coarsening of oxide, pulverization of oxide, and exfoliation of oxide in high‐temperature and high‐pressure steam environments.

Perovskite/Perovskite Tandem Solar Cells in the Substrate Configuration with Potential for Bifacial Operation.

Perovskite/perovskite tandem solar cells have recently exceeded the record power conversion efficiency (PCE) of single-junction perovskite solar cells. They are typically built in the superstrate configuration, in which the device is illuminated from the substrate side. This limits the fabrication of the solar cell to transparent substrates, typically glass coated with a transparent conductive oxide (TCO), and adds constraints because the first subcell that is deposited on the substrate must contain the wide-bandgap perovskite. However, devices in the substrate configuration could potentially be fabricated on a large variety of opaque and inexpensive substrates, such as plastic and metal foils. Importantly, in the substrate configuration the narrow-bandgap subcell is deposited first, which allows for more freedom in the device design. In this work, we report perovskite/perovskite tandem solar cells fabricated in the substrate configuration. As the substrate we use TCO-coated glass on which a solution-processed narrow-bandgap perovskite solar cell is deposited. All of the other layers are then processed using vacuum sublimation, starting with the charge recombination layers, then the wide-bandgap perovskite subcell, and finishing with the transparent top TCO electrode. Proof-of-concept tandem solar cells show a maximum PCE of 20%, which is still moderate compared to those of best-in-class devices realized in the superstrate configuration yet higher than those of the corresponding single-junction devices in the substrate configuration. As both the top and bottom electrodes are semitransparent, these devices also have the potential to be used as bifacial tandem solar cells.

Bacteria detection in a Kretschmann geometry flow cell at a plasmon-enhanced interface with spectroscopic ellipsometer

In this work, we investigate whether bacteria can be substantially examined in liquid environment with an ellipsometer in the visible wavelength range. For that investigation a Kretschmann type flow cell was used in which the paths of illuminated and reflected light beams are on the substrate side. To enhance the sensitivity a thin gold layer was applied on the top of glass substrate and the measurement was performed by using surface plasmon polaritons. Porphyrin functionalized coating layers were employed to analyze their performance to capture bacteria and to study the stability and repeatability of the optical response with regard to the ellipsometric measurement. Escherichia coli (E. coli) bacteria were used as first model bacteria and their deposition on the sensing surface was monitored in a real-time measurement in a liquid environment.

Multiband hybrid MIMO DRA for Sub‐6 GHz 5G and WiFi ‐6 applications

This paper inspects a parasitic element-based inverted meandered U-shaped printed line fed hybrid MIMO DRA. The feed of a single element of the 2-elements hybrid MIMO DRA consists of a meandered shaped line coupled to the inverted L-shaped parasitic element printed on the top side of FR-4 substrate with a partial ground on the back. The rectangular-shaped alumina dielectric is placed over the feed to form the single element hybrid DRA. The individual element resonating at 3.40–4.32 GHz (23.83%) and 4.96–5.05 GHz (1.80%) achieves the dual-band characteristics by exciting multiple modes within the rectangular dielectric resonator. The low-profile Multiple Input–Multiple Output (MIMO) antenna configuration having an overall size of 0.57 λ × 0.23 λ × 0.14 λ mm3consists of two orthogonally placed hybrid rectangular DRAs. The inter-element isolation for a connected ground MIMO structure is better than 22 dB in the desired bands of operation without using any isolation improvement techniques. The MIMO diversity parameters are simulated and measured to validate the MIMO performance. The diversity metrics envelope correlation coefficient is below .175, and .15, the mean effective gain ratio is 0 dB, the total active reflection coefficient values are below 15 dB, and channel capacity loss values are below 0.5 bits/sec/Hz in the lower, and upper bands of operation which are within the recommended practical limits. The presented MIMO design achieved the peak gain of 12.87dBi, and minimum radiation efficiency of 83%, with stable radiation characteristics that make the antenna suitable for Sub-6 GHz 5G and WiFi-6 applications.

(Invited) Short Channel Coplanar Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors on Polyimide Substrate for High Resolution Displays

High-resolution active-matrix organic light-emitting diode (AMOLED) thin-film transistor (TFT) backplane with lower power consumption is needed for augmented reality (AR) applications. The near-to-eye format of AR terminals needs facing several technical challenges, such as higher optical efficiency, wider field of view, lighter weight, and smaller size to accelerate widespread applications. For these reasons, downscaling of TFTs with amorphous-indium-gallium-zinc-oxide (a-IGZO) or LTPS is required. The channel length should be less than 1 μm and the flexible substrate is better than glass because of light weight and very thin structure. TFT technologies on polyimide (PI) substrate can support the applications for foldable and rollable displays. For flexible AMOLED, PI layer of 10 to 20 um is widely used for foldable displays. The PI layer is coated by slot coating on the top of a carrier glass with a buffer layer of carbon nanotubes (CNTs) and graphene oxide (GO) mixture coated by spray. This layer can reduce the adhesion force between PI and glass and thus mechanical detachment can be possible. The CNTs are conducting so that it can release the electrostatic discharge (ESD) damage because CNTs/GO layer exists on the bottom side of the PI substrate. The PI substrate is covered by SiO2 and ZrAlOx layers (five layers in total starting with SiO2) by plasma enhanced chemical vapor deposition and spray pyrolysis, respectively, which acts as a gas barrier. The amorphous ZrAlOx film by spray coating can be used as a high-k gate insulator and also a gas barrier. The threshold voltage of a-IGZO TFTs tends to shift toward negative gate voltage with decreasing the channel length. In this work, a ZrAlOx passivation layer is introduced for the short channel, coplanar a-IGZO TFT. A very thin ZrAlOx layer is deposited by spray pyrolysis on the top of a-IGZO TFT at the substrate temperature of 350 ℃ before interlayer deposition. The a-IGZO TFT with a very thin ZrAlOx layer exhibits the stable threshold voltage dependence with decreasing the channel length. The 0.8 μm channel length a-IGZO TFT with ZrAlOx layer by spray pyrolysis at the substrate temperature of 350 ℃ exhibits the field-effect mobility of 7.09 cm2 V-1 s-1, the threshold voltage of -0.6 V, and on/off current ratio of 3.3 × 107. The formation of Zr-O bonds on the a-IGZO surface region reduces the carrier concentration in the a-IGZO TFT offset region, between source/drain contact and the channel, and blocks the carrier diffusion into the channel. This is the first reported self-aligned coplanar a-IGZO TFT under 1 μm channel length on a flexible substrate. Figure 1

(2021-2022 ECS Toyota Young Investigator Fellowship) Understanding and Suppression of Cation Transport into Polymer Electrolyte Membrane Fuel Cell

Polymer electrolyte membrane fuel cells (PEMFCs) are a viable zero-emissions option for the electrification of the heavy duty transportation sector. However, PEMFCs still suffer from degradation of materials over the fuel cell lifetime. Cation contaminants can be generated from corrosion of bipolar plates and balance of plant components, water contaminants, and environmental sources (e.g., Fe3+, Ca2+, Na+), making them present in the fuel or oxidant stream during operation(1). Cations have been shown to be detrimental to the performance of the PEMFC by reducing water uptake, ionic conductivity, and O2 transport, resulting in performance loss and degradation. Metal cations such as Fe3+ can also lead to chemical degradation of the membrane ionomer (2-4). It is critical to understand the mechanism and rate of cation transport from the bipolar plate channel to the membrane to develop mitigation strategy to suppress the cation transport.In this work, we present the study of the cation (Fe3+) transport mechanism through the gas diffusion layer (GDL) by introducing a cation solution in the cathode channel. Transport rates across the GDL are studied using an ex-situ GDL holder where Fe solution is introduced in the GDL substrate side with water transported through to the microporous layer side (MPL) and is collected and analyzed for Fe concentration, as shown in Figure 1a. Effect of the Fe concentration on transport rates is also studied using computational modeling. Understanding of the transport mechanism is then leveraged to identify mitigation solutions and suppress cation transport from the flow field to the electrode using a GDL with dual MPL architecture as shown in Figure 1b. Optimization of the dual MPL architecture for both durability and performance is also presented. Acknowledgements This research is supported by the 2021-2022 ECS Toyota Young Investigator fellowship and U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office, through the Million Mile Fuel Cell Truck Consortium (M2FCT). Authors acknowledge the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL). References D. D. Papadias, R. K. Ahluwalia, J. K. Thomson, H. M. Meyer, M. P. Brady, H. L. Wang, J. A. Turner, R. Mukundan and R. Borup, Journal of Power Sources, 273, 1237 (2015).R. K. Ahluwalia, D. D. Papadias, N. N. Kariuki, J. K. Peng, X. P. Wang, Y. F. Tsai, D. G. Graczyk and D. J. Myers, Journal of the Electrochemical Society, 165, F3024 (2018).J. P. Braaten, X. M. Xu, Y. Cai, A. Kongkanand and S. Litster, Journal of the Electrochemical Society, 166, F1337 (2019).A. Kneer, J. Jankovic, D. Susac, A. Putz, N. Wagner, M. Sabharwal and M. Secanell, Journal of The Electrochemical Society, 165, F3241 (2018). Figure 1

X-Band Nearfield Shielding Metasurface With Adjustable Reflection/Transmission Zeroes

We introduce, for the first time, a new class of flexible bandstop frequency selective surface that provides very stable nearfield (NF) characteristics in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band, unlike the traditional FSSs. The structure's building block uses two layers of patches to reach the NF stability through their interaction. Periodic convoluted square loops on one side of a flexible substrate and periodic square loops on the other side are used. The created multipole resonator operates by changing the local coupling effect between the cells on the sides. It enables a localization of capacitive and inductive characteristics, which provides spatial filtering for both near- and farfield. An accurate equivalent circuit model is developed to validate the coupling effect. It is shown that four operating modes could be defined for the structure, each of which provides specific behavior. A realization for each operational mode is also provided. An <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band NF shielding of at least 30 dB at the center frequency and maximum 10-dB fractional bandwidth of 32% are obtained. The superiority of the NF shielding performance is shown through comparisons among conventional shields. Finally, the measurement results justify the reliable NF shielding performance.

Marangoni convection instabilities in an evaporating droplet on a non-isothermal substrate

• The maximum number of LRs is smaller than that on the isothermal substrate • The instability patterns preferentially occur at the lower temperature side • LRs continuously propagate along azimuthal direction towards cold side • Propagation speed increases with increase of the temperature gradient • Critical contact angles for the onset of LRs decrease with increasing Ma The Marangoni convection instabilities are investigated in a sessile ethanol droplet as it evaporates on a non-isothermal substrate. The instability structures consistently, preferentially occur at the lower temperature side of substrate. Drifted by the azimuthal thermocapillary flow under externally imposed temperature gradient, the longitudinal rolls are found to propagate from the hot side to the cold side for the droplet, while a radial propagation of the BM cells directly from the cold side to the hot side along the droplet diameter occurs at the last period of evaporation process. The azimuthal propagation speed of longitudinal rolls increases with the increase of temperature gradient, but is independent of the mean temperature of the substrate. Effects of the mean temperature of substrate and the temperature gradient on the Marangoni instabilities are investigated, and the critical conditions for the onset of longitudinal rolls are determined.

Norman window slot antenna with sectoral feed backed by linear phase reflector for ultra wideband applications

An ultra wideband (UWB) slot antenna is proposed, developed, and experimentally validated in this article. The Norman window-shaped UWB slot antenna demonstrates stable radiation characteristics in both directions—zenith (θ = 0°) and nadir (θ = 180°) over the entire UWB frequency range (3.1–10.6 GHz) as observed in both simulations and experiments. A linear phase reflecting UWB frequency selective surface (FSS) is proposed by printing two orthogonal layers of pair of double rectangular loops on the same side of dielectric substrate as a merged frequency selective surface (MFSS). The UWB MFSS is then loaded with the slot antenna and the impact of MFSS on the impedance and radiation characteristics in different configurations of antenna and MFSS together is studied. One configuration with optimum solution is developed for experimental validations followed by the analysis of its radiation characteristics. The proposed antenna demonstrates a directional radiation pattern due to suppression of back lobe radiation when integrated with the UWB MFSS. The proposed antenna demonstrates maximum gain of 7.86 dB with a gain enhancement of 3.6 dB in boresight (θ = 0°) direction when MFSS is applied as a reflector to opposite side of the antenna slot.

Ni-modified carbon nanotube macrofilms supporting NiFe with stable structure for efficient oxygen evolution reaction

The CMF-Ni substrate with high hydrophilicity and good electrical conductivity can induce spherical NiFe particles with strong structure to tightly anchor on the CMF surface, demonstrating fast charge-transfer kinetics and good cycling stability. • Ni-modified CMF presented increased hydrophilicity and electrical conductivity. • The CMF-Ni substrate could induce spherical NiFe to tightly anchor on CMF surface. • NiFe particles were encapsulated with oxyhydroxide (NiFeOOH) thin layers. • The binder-free NiFe/CMF-Ni electrode exhibited enhanced cycling stability. • Excellent activity was ascribed to the strong interaction between NiFe and CMF-Ni. A substrate with good hydrophilicity and conductivity is essential to design a binder-free efficient catalyst for oxygen evolution reaction (OER). In this work, We introduced Ni particles onto one side of the carbon macro-film (CMF) surface (CMF-Ni) via electrodeposition method. The hydrophilicity and conductivity of the CMF-Ni could be increased sharply compared to the CMF. And then spherical NiFe particles could be tightly anchored on the CMF side of the CMF-Ni substrate. Compared to the NiFe/CMF with flower-like structure prepared by using bare CMF as a substrate, the obtained NiFe/CMF-Ni with sandwich structure could be directly used as a binder-free electrode and exhibited higher stability and faster catalytic reaction kinetics. There is no obvious change of morphology and microstructure for the NiFe/CMF-Ni electrode after OER stability test at 1.54 V@50 mA cm −2 after 24 h. The main reasons for this result are that NiFe particles are mainly encapsulated with NiFeOOH thin layers and intertwined with carbon nanotubes, thereby possessing good corrosion resistance. This work not only fabricates an efficient binder-free electrode but also more importantly provides a facile substrate strategy, which can pave the way for effective integrated electrodes fabricating and their stability boosting.

Quench Protection Study of a Large Scale REBCO Magnet With Additional Copper Tapes

REBCO coated conductors (CCs) are expected to be applied to high field magnets due to their high longitudinal tensile strength and excellent critical current characteristics in high fields. For large scale magnets with large stored energy, quench protection is a key issue. Although various quench protection methods have been proposed for REBCO magnets, the most traditional and straight forward approach is to increase the copper stabilizer and reduce the current density. This approach leads to a significant increase in conductor length to generate a required magnetic field in case a small bore diameter magnet, while the conductor increase would not be serious in case a large bore diameter one. Based on this approach, we have successfully fabricated a practical cryogen-free superconducting magnet (CSM) with a large bore of 200 mm-diameter and a central field of 5 T using REBCO CCs laminated with 0.3 mm-thick copper tapes. For further study, we designed a MJ-class 10 T-CSM with the same inner-diameter as the 5 T-CSM and investigated the feasibility of the magnet through quench tests in this study. We conducted quench tests on short samples of copper-plated REBCO CCs with copper tape soldered on different surfaces, and quench tests on a small coil assuming an energy recovery method with external resistance. In the short sample tests, it was found that the temperature rise was suppressed regardless of the position of the copper tape lamination, and the normal zone propagation velocity was improved when the copper tape was laminated to the substrate side. In the small coil tests, the decay time constant after shutdown was varied to find the conditions that can protect the magnet with high stored energy. We confirmed that quench protection of 10 T-CSM was feasible under practical conditions.

Ultrathin chiral metasurface with multiple functionalities

This paper presents an ultrathin multiband chiral metasurface having good angular stability. The metasurface consists of two patterned metallic sheets placed on opposite sides of a microwave substrate. It has twelve operational bands. It achieves asymmetric linear-to-circular polarization transmission within three frequency bands and asymmetric cross-polarized transmission of linearly polarized incident waves within seven frequency bands. It also exhibits two symmetric co-polarized transmission bands for both x- and y-directed incident E-field orientations. The structure gives favorable response for incident angles up to 60° till 11 GHz and up to 40° from 11 to 13 GHz for both transverse-electric and transverse-magnetic incidence. Its ultrathin nature makes it lightweight. The twelve operational frequency bands of the metasurface can be tuned and adjusted to meet user specifications.

Spray Coated Cellulose Nanofiber (CNF) Film as an Eco-Friendly Substrate for Flexible and Printed Electronics

Cellulose nanofiber is an eco-friendly nanomaterial used for fabricating various functional materials. It is an alternative for synthetic plastic and other petroleum derived materials. Due to demand of CNF film, fast and rapid method for fabrication of CNF film is required. A new method on spray coating to prepare smooth cellulose nanofiber (CNF) films was developed. In this method, spraying CNF suspension onto a smooth and polished metal surface was carried out and then allowed the spray coated wet film to dry in air under standard laboratory conditions. Spraying has notable advantages such as contour coating and contactless coating with the base substrate. The basis weight and thickness of the CNF film is tailorable by adjusting CNF suspension in spraying process. CNF film prepared via spray coating has unique two-sided surface roughness with the surface in contact with the base substrate or metal side much smoother than the air-contact side. The surface roughness is one of the controlling parameter in the application of the CNF film as a substrate for flexible and printed electronics. The RMS roughness of the two surfaces investigated by Optical Profilometry [OP] was found to be 2087 nm on the rough side and 389 nm on the spray coated side, respectively. The spray coated CNF film has ultra-high smoothness on the side exposed to the polished stainless steel surface. The factors including the size of cellulose fibrils and surface smoothness of base surface that control the roughness of the film are currently being investigated and will be discussed in this chapter. The surface smoothness requirements for substrate applications in flexible and printed electronics will be discussed.

The dependence of fracture mode on interfacial microstructure in TA1 pure titanium/AgCuNi/304 stainless steel vacuum brazed joints

Vacuum brazing of TA1/304 stainless steel (SS) was systematically investigated by changing the composition of filler metal, brazing temperature and holding time. The AgCuNi (70.75Ag–28Cu-1.25Ni, wt.%) filler metal was selected to eliminate the excessive TixCuy and TixFey phases in the weld. The defect-free joint with the shear strength of 148.5 MPa was obtained under the vacuum degree of 10−4 Pa, the brazing temperature of 880 °C and the holding time of 10 min. The holding time affected the formation and distribution of Ti3Cu4 phase and the brazing temperature affected the formation of TiCu4 phase and TixFey phases, which caused the cracks at the interface between the weld and the substrates. The excessive TiCu4 phase and TixFey phases near the 304 SS substrate's side led to the transition of the shear section from the entire weld to the interface between the weld and the 304 SS substrate.

Dual rhombic loop‐based frequency selective surfaces for X‐band applications

AbstractDual rhombic loop (DRL) based low‐cost X‐band frequency selective surfaces (FSSs) with stopband characteristics are presented in this study. Orthogonally oriented arrays of rhombic loop pairs are printed back‐to‐back (BTB) on both sides of dielectric substrate to achieve wide stopband characteristics with stable response under oblique incidences. The nonlinearities in the reflection phase of BTB DRL printed FSSs are compensated by printing orthogonally oriented rhombic loop pairs on the same side of the substrate. Merging orthogonally oriented rhombic loop pairs results in a single‐layer wide stopband FSS with linear reflection phase under normal incidence. Both polarization dependent merged DRL (MDRL) and independent BTB DRL FSSs are developed and experimentally validated. As per measurements, the BTB printed FSS array exhibits 4.3 GHz wide stopband with transmission nulls at 7.9 and 10 GHz while the single side printed FSS exhibits 3.7 GHz wide stopband with transmission null at 8.3 GHz.

Fully Textile Dual-Band Logo Antenna for IoT Wearable Devices.

In recent years, the interest in the Internet of Things (IoT) has been growing because this technology bridges the gap between the physical and virtual world, by connecting different objects and people through communication networks, in order to improve the quality of life. New IoT wearable devices require new types of antennas with unique shapes, made on unconventional substrates, which can be unobtrusively integrated into clothes and accessories. In this paper, we propose a fully textile dual-band logo antenna integrated with a reflector for application in IoT wearable devices. The proposed antenna’s radiating elements have been shaped to mimic the logo of South-West University “Neofit Rilski” for an unobtrusive integration in accessories. A reflector has been mounted on the opposite side of the textile substrate to reduce the radiation from the wearable antenna and improve its robustness against the loading effect from nearby objects. Two antenna prototypes were fabricated and tested in free space as well as on three different objects (human body, notebook, and laptop). Moreover, in the two frequency ranges of interest a radiation efficiency of 25–38% and 62–90% was achieved. Moreover, due to the reflector, the maximum local specific-absorption rate, which averaged over 10 g mass in the human-body phantom, was found to be equal to 0.5182 W/kg at 2.4 GHz and 0.16379 W/kg at 5.47 GHz. Additionally, the results from the performed measurement-campaign collecting received the signal-strength indicator and packet loss for an off-body scenario in real-world use, demonstrating that the backpack-integrated antenna prototype can form high-quality off-body communication channels.

An internal docking site stabilizes substrate binding to γ-secretase: Analysis by molecular dynamics simulations

Amyloid precursor protein (APP) is cleaved and processed sequentially by γ-secretase yielding amyloid β (Aβ) peptides of different lengths. Longer Aβ peptides are associated with the formation of neurotoxic plaques related to Alzheimer’s disease. Based on the APP substrate-bound structure of γ-secretase, we investigated the enzyme-substrate interaction using molecular dynamics simulations and generated model structures that represent the sequentially cleaved intermediates during the processing reaction. The simulations indicated an internal docking site providing strong enzyme-substrate packing interaction. In the enzyme-substrate complex, it is located close to the region where the helical conformation of the substrate is interrupted and continues toward the active site in an extended conformation. The internal docking site consists of two non-polar pockets that are preferentially filled by large hydrophobic or aromatic substrate side chains to stabilize binding. Placement of smaller residues such as glycine can trigger a shift in the cleavage pattern during the simulations or results in destabilization of substrate binding. The reduced packing by smaller residues also influences the hydration of the active site and the formation of a catalytically active state. The simulations on processed substrate intermediates and a substrate G33I mutation offer an explanation of the experimentally observed relative increase of short Aβ fragment production for this mutation. In addition, studies on a substrate K28A mutation indicate that the internal docking site opposes the tendency of substrate dissociation due to a hydrophobic mismatch at the membrane boundary caused by K28 during processing and substrate movement toward the enzyme active site. The proposed internal docking site could also be useful for the specific design of new γ-secretase modulators.

Reconfigurable multiband nano-antenna design for photonic applications

The Antenna that comprises metal patches set on the Dielectric which is given by coplanar transmission line is known to be a patch antenna. It can also be known as Microstrip patch antenna. The foremost downside is the efficiency of the antenna. A M-patch antenna includes a patch i.e a radiating patch, ground plane on one side and a thin flat metallic region on the other side of dielectric substrate. There are various feed methods such as offset feed, centre feed, inset feed and quarter wave line feed. Microstrip patch antennas have better advantages over conventional antennas. In this paper we develop Multiband Antenna for photonic application. The proposed antenna is designed in a patch model. And in the patch, a cylindrical shape graphene is placed over the patch in which we use this for photonic application. And this antenna is designed in flexible material such as copper tape, Kaptonmaterial and nano materials. Nano based cylindrical antenna was not done previously.In this, we have achieved a gain of 8dB which is comparatively better with other antenna after many implementation.

Can P- and Oxidized P-doped Graphene be a Good Anode for Na-Ion Batteries?: A First-Principles Assessment

Sodium ion batteries (NIBs) become an important emerging alternative to lithium ion batteries (LIBs) because of low cost and suitability for large-scale applications. However, optimizing anodes in NIBs is still a challenge. In this paper, we investigated the possibility of using P- and oxidized P-doped graphene as an anode in NIBs. We reveal important fundamental properties of sodium adsorption on P- and oxidized P-doped graphene by employing first principles calculations. Our results suggest that Na adsorption on the single side of substrate followed by on the other side is the preferred configuration with high Na capacity of 511 mAh g−1. Na is predicted to migrate with a low diffusion barrier near the protrudent P and OP on the substrate. Although Na has to cross an elevated diffusion barrier to escape from the most stable site interacting with the P and OP, this can be significantly mitigated by increasing the adsorbed Na concentration. Our calculations also demonstrate the structures mostly maintain the metallic properties thus shows high electron mobility upon a wide range of sodiation level. Our findings indicate that P- and oxidized P-doping of graphene anodes can be a promising route toward increasing the overall performance of NIBs for practical application.

Explorations Into the Viability of High Voltage Bipolar Na-Ion Cells Using Liquid Electrolytes

Bipolar electrodes can be defined as electrodes where cathode and anode active materials exist on either side of a shared current collector substrate. The resultant rechargeable bipolar batteries, using series-connected electrochemical cells within one sealed enclosure, can enable high-voltage systems irrespective of the voltage of the cathode//anode couple used. The sodium-ion battery, being well-suited for the bipolar concept, is now rapidly being commercialized and has higher energy densities than most rechargeable battery technologies. However, bipolar sodium-ion batteries using commercially-feasible liquid electrolytes and manufacturing methodologies, have not been demonstrated at scale yet. Herein, we explore the design methodology needed to enable commercial realization of such bipolar sodium-ion batteries, using liquid electrolytes and different types of cathode//anode couples. We show good cycling stabilities over 200 cycles and potential for voltages beyond 6 V for bipolar Na-ion pouch cells. We also introduce a scalable method to fabricate nSmP Na-ion/mixed-chemistry bipolar cells (n cells in series; m cells in parallel) in a single, sealed cell. Our results point to realistic promise for high voltage and sustainable bipolar sodium-ion batteries.